AB0028 LEUCOCYTE ABNORMALITIES IN SYNOVIAL FLUID OF DEGENERATIVE AND INFLAMMATORY ARTHROPATHIES
Authors: C. Baggio, R. Luisetto, C. Boscaro, A. Scanu, R. Ramonda, M. Albiero, P. Sfriso, F. Oliviero
Journal: Annals of the Rheumatic Diseases (2023)

<h3>Background</h3> Genome damage has been related to the induction of autoimmune processes, chronic inflammation, and apoptosis. Recent studies suggest that some rheumatological disease are associated with overall genomic instability in the T cell compartment [1,2]. However, no data regarding leucocytes abnormalities in synovial fluid (SF) and their relationship with inflammation are available. <h3>Objectives</h3> The aim of this study was to investigate cellular phenotypes in SF collected from patients with different inflammatory arthropathies, including rheumatoid arthritis (RA), psoriatic arthritis (PsA), crystal-induced arthritis (CIA) and non-inflammatory arthropathies such as osteoarthritis (OA). <h3>Methods</h3> SFs were collected by arthrocentesis from swollen knees of untreated adult patients with RA (n = 6), PsA (n = 12), CIA (n = 10), and OA (n = 7). Total white blood cell (WBC) count was performed using a Bürker counting chamber. Differential leucocyte count was performed by microscopic examination of 300 cells on May Grunwald Giemsa-stained preparations (MGG). Crystal search was performed using compensated polarized light microscopy. MGG staining was used for studying cellular morphology and to perform a cytogenic evaluation of leucocytes. All slides were examined for micronuclei (MN) and nuclear abnormality (NA) included binucleated cells, and karyolitic, karyorrhectic, and pyknotic cells. The following cytokines, chemokines and growth factors were measured in SFs using commercially available ELISA kits: interleukin (IL)-1β, IL-6, IL-8, IL-10, TGFβ, and TNFα. The expression levels of factors involved in apoptosis such as BCL-2, BAK, BID, BAD and BAX were measured by real-time quantitative PCR (qPCR). Caspase-3 activity was determined using commercially available colorimetric assay kit. <h3>Results</h3> We found high percentage of MN in SF from CIA and RA compared to the OA group (p&lt;0.05) and a high frequency of pyknotic cell in RA (p&lt;0.05) and CIA patients (p&lt;0.01). The percentage of karyorrhectic and karyolitic cells were higher in RA patients with respect to OA and PsA patients (p&lt;0.05). A correlation between pyknosis and immature polymorphonuclear cells with local inflammatory indices was observed. A strong positive correlation between local inflammatory cellular indices including WBC and PMN and the cytokines IL-1β, IL-6, IL-8, IL-10 was found. The study of apoptosis process revealed an increased BAX expression in CIA (p&lt;0.05) and RA (p&lt;0.08) compared to OA and PsA, while Bcl-2 was higher in CIA (p&lt;0.05). Caspase-3 activity was increased in SF from RA patients compared to OA and PsA (p&lt;0.05) and correlates with inflammatory and anti-inflammatory cytokines (IL-1β, IL-8, IL-10). <h3>Conclusion</h3> Our results showed that inflammatory SF are associated with genomic instability and abnormal cell subsets. A deeper knowledge of different abnormal cell subsets and their function could lead to a better understanding of the mechanisms underlying in the resolution of inflammation in these diseases. <h3>References</h3> [1]Shao, L. DNA Damage Response Signals Transduce Stress From Rheumatoid Arthritis Risk Factors Into T Cell Dysfunction. Front Immunol 2018, 9, 3055. [2]Galita, G., Brzezińska, O., Gulbas, I., Sarnik, J., Poplawska, M., Makowska, J., Poplawski, T. Increased Sensitivity of PBMCs Isolated from Patients with Rheumatoid Arthritis to DNA Damaging Agents Is Connected with Inefficient DNA Repair. Journal of clinical medicine 2020, 9(4), 988. <h3>Acknowledgements:</h3> NIL. <h3>Disclosure of Interests</h3> None Declared.